init: add an init_mknod helper

Add a simple helper to mknod with a kernel space file name and switch
the early init code over to it.  Remove the now unused ksys_mknod.

Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/init/initramfs.c b/init/initramfs.c
index 0489eb6..425adda 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -355,7 +355,7 @@ static int __init do_name(void)
 	} else if (S_ISBLK(mode) || S_ISCHR(mode) ||
 		   S_ISFIFO(mode) || S_ISSOCK(mode)) {
 		if (maybe_link() == 0) {
-			ksys_mknod(collected, mode, rdev);
+			init_mknod(collected, mode, rdev);
 			init_chown(collected, uid, gid, 0);
 			init_chmod(collected, mode);
 			do_utime(collected, mtime);